Emergency Position-Indicating Radio Beacon

The Emergency Position-Indicating Radio Beacon ranks among the most important pieces of life-saving equipment on a ship and a core element of the GMDSS. It is a self-contained radio beacon that, once activated, transmits a coded distress signal on the international 406 MHz frequency to the Cospas-Sarsat network of satellites. These satellites relay the alert to ground stations and on to rescue coordination centres, so that within minutes of activation the authorities know that a specific vessel is in distress and, crucially, where it is.

What makes the EPIRB so effective is the information its signal carries and the way it activates. Each beacon is registered and encoded with a unique identity linked to the ship, so rescuers know which vessel has triggered it and can consult its details and emergency contacts. Modern EPIRBs incorporate GPS, so the transmitted position is accurate to within a small radius, greatly reducing the search area. Many also transmit a homing signal on 121.5 MHz that rescue aircraft and vessels can use to find the beacon in the final stage of a search.

Ship EPIRBs are typically mounted in a float-free bracket on an outside deck with a hydrostatic release. If the ship sinks before the crew can deploy the beacon manually, the release lets it float free and it activates automatically on immersion, so a distress alert is sent even in a sudden foundering. EPIRBs are tested regularly, their batteries and hydrostatic releases have expiry dates that must be maintained, and the registration must be kept up to date. Together with search-and-rescue transponders and the wider GMDSS, the EPIRB has saved countless lives by ensuring that a distress alert reaches help quickly and accurately from anywhere on the world's oceans.